1. Field of the Invention
The present invention relates to an information medium provided with a pair of tape reels having a magnetic tape wound therearound, and a casing body rotatably accommodating the tape reels.
2. Description of the Related Art
As an information medium of this kind, there is known a tape cartridge disclosed in Japanese Laid-Open Patent Publication (Kokai) No. 2000-137971. This tape cartridge is comprised of a pair of reels having a magnetic tape wound therearound, a shell formed by an upper half and a lower half, and an upper sheet and a lower sheet disposed in the shell in a manner sandwiching the reels. In this case, each reel includes an inner hollow cylindrical portion in the form of a hollow cylinder, and an outer hollow cylindrical portion formed along the outer periphery of the inner cylindrical portion in a manner continuous therewith. The upper end and the lower end of the inner hollow cylindrical portion are configured such that they protrude from the upper end and the lower end of the outer hollow cylindrical portion, respectively, and the lower end of the inner hollow cylindrical portion is loosely fitted in a reel-receiving portion of the lower half of the shell, whereby the reel is rotatably accommodated in the shell. Further, the inner peripheral surface of the inner hollow cylindrical portion of the reel is formed with convex portions for being engaged with a drive shaft (spindle) of a recording and reproducing device when the drive shafts are inserted.